The conformations and microdynamics of several biologically important molecules in aqueous solution are being investigated by a variety of magnetic resonance techniques including proton and carbon-13 high resolution and relaxation spectroscopy. In particular we are using the newly developed technique of perturbing the NMR spectra of flexible molecules with lanthanide ions and analyzing the resulting spectra with advanced computer methods. With this method we are investigating conformations of the hormones vasopressin and oxytocin, the hormone releasing hormones, thyrotropin releasing hormone and luteinizing hormone releasing hormone as well as the important bile pigments - bilirubin and biliverdin in aqueous and non-aqueous solutions. Using a combination of techniques we are also investigating the conformations of the peptides H-Trp-Met-Asp-Phe-NH2 which is the minimum fragment for gastrin-like activity and the dipeptide Asp-Phe-ome - the so-called "sweet" dipeptide. These studies are pointed directly at structure-function relations. From a very basic standpoint we are performing C13 relaxation studies on normal and specifically deuterated macromolecules - in particular polypeptides - in an effort to understand the amount of non-dipole-dipole contributions to C13 relaxation in these molecules. We wish to provide a firm foundation for relating C13 relaxation times to the microdynamics of motion in these systems. In addition in our capacity as a research resource we are cooperating in projects with members of the Department of Microbiology and Pharmacology on membrane structure and drug-membrane interactions as with members of the Pharmacy and Pharmacology departments on a variety of biosynthetic and structural problems.